Field of the Invention
Embodiments of the present invention relate generally to audiovisual processing and, more particularly, to perspective correction for curved display screens.
Description of the Related Art
Streaming audiovisual (AV) content, such as feature length films and television programs, over the Internet has become increasingly popular as the availability of high-bandwidth Internet connections has expanded. As a result, televisions, computers, smartphones, and set-top boxes increasingly include applications that enable various types of streaming content to be downloaded and viewed. For example, a particular streaming content provider may develop and distribute a streaming content application that is capable of being executed on multiple device platforms, enabling users to view streaming content on a variety of different devices.
One obstacle commonly encountered when implementing a streaming content application across a variety of different devices is accurately testing the calibration of each device and the playback of streaming content in an automated fashion. In particular, because different types of devices have unique hardware characteristics, different devices generally have different playback characteristics as well that impact how the streaming content is displayed on those devices. For example, different television models may have different audio delays, effective resolutions, processing speeds, screen geometries, etc. Consequently, a separate calibration process is typically manually performed for each device model on which a streaming content application is to be implemented to enable the streaming content to be displayed properly on each such device model.
A common technique for calibrating a device is to play a calibration sequence on the device (e.g., via a streaming content application) and record the audio and video output of the device via a camera. However, in order to properly calibrate the device, images of the screen must be accurately captured by the camera, without generating significant distortions. Because the camera typically cannot be perfectly aligned with the display of the device being calibrated, most conventional calibration techniques include perspective correction operations on the captured images before analyzing the images for calibration. These steps are performed to compensate for the camera being tilted, off-angle, and/or too far relative to the display of the device being calibrated.
One drawback of these types of conventional calibration techniques is that, although the techniques are reasonably effective in mitigating camera alignment problems, conventional techniques cannot accurately correct for geometric distortions that are present in devices having curved display screens. As a result, when a calibration algorithm developed for a flat screen display is applied to calibrate a curved screen display, the results are typically inaccurate. Consequently, a custom calibration algorithm must be developed for the specific curvature value of the curved display screen to be calibrated. However, because there are hundreds, if not thousands, of different curvature values implemented across different device brands and models, writing a separate calibration algorithm for each type of curved display would be infeasible.
As the foregoing illustrates, improved techniques for calibrating a curved display screen would be useful.